Flexible high-density mapping catheter tips and flexible ablation catheter tips with onboard high-density mapping electrodes

ABSTRACT

Flexible high-density mapping catheter tips and flexible ablation catheter tips with onboard high-density mapping electrodes are disclosed. These tips can be used for diagnosing and treating cardiac arrhythmias. The flexible, distal tips are adapted to conform to tissue and comprise a plurality of microelectrodes mounted to permit relative movement among at least some of the microelectrodes. The flexible tip portions may comprise a flexible framework forming a flexible array of microelectrodes (for example, a planar or cylindrical array) adapted to conform to tissue and constructed at least in part from nonconductive material in some embodiments. The flexible array of microelectrodes may be formed from a plurality of rows of longitudinally-aligned microelectrodes. The flexible array may further comprise, for example, a plurality of electrode-carrying arms or electrode-carrier bands. Multiple flexible frameworks may be present on a single device. A delivery adapter having an internal compression cone is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/670,678, filed 31 Oct. 2019, which is a continuation of U.S.application Ser. No. 14/760,682, filed 13 Jul. 2015, now U.S. Pat. No.10,492,729, issued 3 Dec. 2019, which is a national stage filing basedupon international application no. PCT/US2014/011940, filed 16 Jan. 2014and published in English on 24 Jul. 2014 under international publicationno. WO 2014/113612 A1, which claims priority to U.S. provisionalapplication No. 61/753,429, filed 16 Jan. 2013. This application isrelated to U.S. provisional application No. 60/939,799, filed 23 May2007; U.S. application Ser. No. 11/853,759, filed 11 Sep. 2007, now U.S.Pat. No. 8,187,267, issued 29 May 2012; U.S. provisional application No.60/947,791, filed 3 Jul. 2007; U.S. application Ser. No. 12/167,736,filed 3 Jul. 2008, now U.S. Pat. No. 8,206,404, issued 26 Jun. 2012;U.S. application Ser. No. 12/667,338, filed 20 Jan. 2011 (371 date),published as U.S. patent application publication no. US 2011/0118582 A1,now U.S. Pat. No. 8,827,910, issued 9 Sep. 2014; U.S. application Ser.No. 12/651,074, filed 31 Dec. 2009, published as U.S. patent applicationpublication no. US 2010/0152731 A1, now U.S. Pat. No. 8,979,837, issued17 Mar. 2015; U.S. application Ser. No. 12/436,977, filed 7 May 2009,published as U.S. patent application publication no. US 2010/0286684 A1;U.S. application Ser. No. 12/723,110, filed 12 Mar. 2010, published asU.S. patent application publication no. US 2010/0174177 A1, now U.S.Pat. No. 8,734,440, issued 27 May 2014; U.S. provisional application No.61/355,242, filed 16 Jun. 2010; U.S. application Ser. No. 12/982,715,filed 30 Dec. 2010, published as U.S. patent application publication no.US 2011/0288392 A1, now U.S. Pat. No. 8,974,454, issued 10 Mar. 2015;U.S. application Ser. No. 13/159,446, filed 14 Jun. 2011, published asU.S. patent application publication no. US 2011/0313417 A1;international application no. PCT/US2011/040629, filed 16 Jun. 2011,published as international publication no. WO 2011/159861 A2; U.S.application Ser. No. 13/162,392, filed 16 Jun. 2011, published as U.S.patent application publication no. US 2012/0010490 A1; and U.S.application Ser. No. 13/704,619, filed 16 Dec. 2012 (371 date), which isa national phase of international patent application no.PCT/US2011/040781, filed 16 Jun. 2011, published as internationalpublication no. WO 2011/159955 A1. Each of these applications is herebyincorporated by reference as though fully set forth herein.

BACKGROUND a. Field

The instant disclosure relates to high-density mapping catheter tips andto map-ablate catheter tips for diagnosing and treating cardiacarrhythmias via, for example, radiofrequency (RF) ablation. Inparticular, the instant disclosure relates to flexible high-densitymapping catheter tips, and to flexible ablation catheter tips that alsohave onboard high-density mapping electrodes.

b. Background Art

Catheters have been used for cardiac medical procedures for many years.Catheters can be used, for example, to diagnose and treat cardiacarrhythmias, while positioned at a specific location within a body thatis otherwise inaccessible without a more invasive procedure.

Conventional mapping catheters may include, for example, a plurality ofadjacent ring electrodes encircling the longitudinal axis of thecatheter and constructed from platinum or some other metal. These ringelectrodes are relatively rigid. Similarly, conventional ablationcatheters may comprise a relatively rigid tip electrode for deliveringtherapy (e.g., delivering RF ablation energy) and may also include aplurality of adjacent ring electrodes. It can be difficult to maintaingood electrical contact with cardiac tissue when using theseconventional catheters and their relatively rigid (or nonconforming),metallic electrodes, especially when sharp gradients and undulations arepresent.

Whether mapping or forming lesions in a heart, the beating of the heart,especially if erratic or irregular, complicates matters, making itdifficult to keep adequate contact between electrodes and tissue for asufficient length of time. These problems are exacerbated on contouredor trabeculated surfaces. If the contact between the electrodes and thetissue cannot be sufficiently maintained, quality lesions or accuratemapping are unlikely to result.

The foregoing discussion is intended only to illustrate the presentfield and should not be taken as a disavowal of claim scope.

BRIEF SUMMARY

The instant disclosure relates to high-density mapping catheter tips andto map-ablate catheter tips for diagnosing and treating cardiacarrhythmias via, for example, RF ablation. In particular, the instantdisclosure relates to flexible high-density mapping catheter tips, andto flexible ablation catheter tips that also have onboard high-densitymapping electrodes. Some embodiments include irrigation.

In one embodiment, a high-density mapping catheter comprises anelongated catheter body comprising a proximal end and a distal end, anddefining a catheter longitudinal axis extending between the proximal anddistal ends; and a flexible, distal tip assembly at the distal end ofthe catheter body and adapted to conform to tissue, the flexible distaltip assembly comprising a plurality of microelectrodes mounted so thatat least some of the microelectrodes are moveable relative to other ofthe microelectrodes.

In another embodiment, a high-density mapping catheter comprises thefollowing: (i) a catheter shaft comprising a proximal end and a distalend, the catheter shaft defining a catheter shaft longitudinal axisextending between the proximal end and the distal end; (ii) a flexibletip portion located adjacent to the distal end of the catheter shaft,the flexible tip portion comprising a flexible framework comprisingnonconductive material; and (iii) a plurality of microelectrodes mountedon the flexible framework and forming a flexible array ofmicroelectrodes adapted to conform to tissue; wherein the flexibleframework is configured to facilitate relative movement among at leastsome of the microelectrodes relative to other of the microelectrodes;and wherein the nonconductive material insulates each microelectrodefrom other microelectrodes. The flexible array of microelectrodes maybe, for example, a planar or cylindrical array of microelectrodes formedfrom a plurality of rows of longitudinally-aligned microelectrodes. Theflexible array may further comprise, for example, a plurality ofelectrode-carrying arms or electrode-carrier bands.

In yet another embodiment, a flexible, high-density mapping-and-ablationcatheter comprising the following: (a) a catheter shaft comprising aproximal end and a distal end, the catheter shaft defining a cathetershaft longitudinal axis; (b) a first plurality of microelectrodesmounted on a first flexible framework of nonconductive material andforming a first flexible array of microelectrodes adapted to conform totissue; wherein the first flexible framework is configured to facilitaterelative movement among at least some of the microelectrodes; andwherein the nonconductive material insulates each microelectrode fromother microelectrodes; and (c) a flexible tip portion located adjacentto the distal end of the catheter shaft, the flexible tip portioncomprising a second flexible framework constructed from conductivematerial.

In another embodiment, a flexible, high-density mapping-and-ablationcatheter comprising the following: (i) a catheter shaft comprising aproximal end and a distal end, the catheter shaft defining a cathetershaft longitudinal axis; (ii) a first plurality of microelectrodesmounted on a first flexible framework of nonconductive material andforming a first flexible array of microelectrodes adapted to conform totissue; wherein the first flexible framework is configured to facilitaterelative movement among at least some of the microelectrodes in thefirst plurality of microelectrodes relative to other of themicroelectrodes in the first plurality of microelectrodes; and whereinthe nonconductive material insulates each microelectrodes in the firstplurality of microelectrodes from other microelectrodes in the firstplurality of microelectrodes; (iii) a second plurality ofmicroelectrodes mounted on a second flexible framework of nonconductivematerial and forming a second flexible array of microelectrodes adaptedto conform to tissue; wherein the second flexible framework isconfigured to facilitate relative movement among at least some of themicroelectrodes in the second plurality of microelectrodes relative toother of the microelectrodes in the second plurality of microelectrodes;and wherein the nonconductive material insulates each microelectrodes inthe second plurality of microelectrodes from other microelectrodes inthe second plurality of microelectrodes; and (iv) an ablation regionlocated between the first flexible framework and the second flexibleframework.

In still another embodiment, a delivery adapter comprises a body thatcomprises a dilator support pocket, an internal compression cone, and aguide sheath connector. The delivery adapter body may be separable orsplittable into a first portion and a second portion.

The foregoing and other aspects, features, details, utilities, andadvantages of the present disclosure will be apparent from reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary, isometric view of a high-density mappingcatheter according to a first embodiment.

FIG. 2 is an isometric, fragmentary view of the catheter shown in FIG. 1depicted in a flexed configuration, representing contact between thecatheter tip and cardiac tissue.

FIG. 3 is a fragmentary view of the flat pattern design of an electrodecarrier band (or ‘carrier band’) according to the first embodiment shownin FIGS. 1 and 2.

FIG. 4 is a fragmentary, isometric view of a high-density mappingcatheter according to a second embodiment.

FIG. 5 is a fragmentary, isometric view of the catheter depicted in FIG.4 shown in a flexed configuration, representing contact between thecatheter tip and cardiac tissue.

FIG. 6 is a fragmentary, isometric view of a catheter ablation tiphaving distal high-density mapping electrodes according to a thirdembodiment.

FIG. 7 is an enlarged, fragmentary view of the circled portion of FIG.6.

FIG. 8 is a fragmentary, isometric view of an ablation and high-densitymapping catheter tip according to a fourth embodiment.

FIG. 9 is a fragmentary, isometric view of the catheter tip depicted inFIG. 8 shown in a partially-flexed or bent configuration, simulatingcontact between the catheter tip and cardiac tissue.

FIG. 10 is a fragmentary, isometric view of a catheter tip of ahigh-density mapping catheter according to a fifth embodiment.

FIG. 11 is a fragmentary, side view of the catheter tip depicted in FIG.10.

FIG. 12 is a flat pattern design of the materials forming a portion ofthe catheter tip depicted in FIGS. 10 and 11, clearly showingalternating electrode-carrier bands (or ‘carrier bands’) separated by aplurality of linking bands.

FIG. 13 depicts an isolated pad structure from a carrier band depictedin FIG. 12 and shows the bowtie or hourglass configuration, including amicroelectrode mounting aperture.

FIG. 14 depicts two pad structures from one of the carrier bandsdepicted in FIG. 12 including a circumferential connector extendingbetween the pad structures.

FIG. 15 is a fragmentary view of the distal end of the catheter depictedin, for example, FIGS. 10 and 11, with portions of the catheter removedto reveal internal structures.

FIG. 16 is similar to FIG. 15, revealing additional internal structuresof the catheter tip depicted in, for example, FIGS. 10, 11, and 15.

FIG. 17 is a fragmentary view of the tip portion of a high-densitymapping catheter according to a sixth embodiment, before themicroelectrodes (or ‘button electrodes’) are mounted.

FIG. 18 is similar to FIG. 12, but depicts the flat pattern design usedto create the catheter tip depicted in FIG. 17, includingelectrode-carrier bands (or ‘carrier bands’), and linking bands that areslightly different from the corresponding structures depicted in FIG.12.

FIG. 19 is similar to FIG. 14, but depicts the pad structures accordingto the sixth embodiment, including inter-band bridges.

FIG. 20 is a fragmentary view of one tab structure from a linking banddepicted in, for example, FIG. 18.

FIG. 21 depicts two tab structures comprising part of a linking banddepicted in FIG. 18, including a tab-structure connector extendingbetween the depicted adjacent tab structures.

FIG. 22 depicts a single linking band (on the left) inter-connected witha single carrier band (on the right) of the design depicted in FIG. 18.

FIG. 23 is a fragmentary, isometric view of the tip of a high-densitymapping catheter according to the sixth embodiment, shown with thethirty-two microelectrodes mounted in the electrode apertures depictedin FIG. 17.

FIG. 24 is an isometric view of the catheter tip depicted in FIG. 23,but shown in a flexed configuration, simulating contact between thecatheter tip and a cardiac wall.

FIG. 25 depicts an entire high-density mapping catheter according to thesixth embodiment, including an electrical connector and a control handletoward the proximal end of the catheter.

FIG. 26 is similar to FIGS. 23 and 24, and shows an enlarged view of thecircled portion of FIG. 25.

FIG. 27 is a fragmentary, isometric view of the tip portion of ahigh-density mapping catheter according to a seventh embodiment.

FIG. 28 depicts the distal tip of a high-density mapping catheteraccording to an eighth embodiment, and includes multiple ring electrodesadjacent to a flexible array of microelectrodes.

FIG. 29 is a fragmentary, isometric view of the tip portion of amap-and-ablate catheter according to a ninth embodiment, including aflexible array of microelectrodes for mapping and a flexible ablationtip located distal of the flexible array of microelectrodes.

FIG. 30 depicts the catheter tip of FIG. 29 in a partially-flexedconfiguration, simulating contact between the ablation tip and cardiactissue.

FIG. 31 depicts the tip portion of a map-and-ablate catheter accordingto a tenth embodiment, including an ablation section straddled byflexible arrays of microelectrodes, and further including two ringelectrodes.

FIG. 32 is another view of the catheter tip depicted in FIG. 31.

FIG. 33 is a fragmentary, isometric view depicting the tip portion of ahigh-density mapping catheter according to an eleventh embodiment.

FIG. 34 is a plan view of the catheter tip depicted in FIG. 33.

FIG. 35 is an elevational view of the catheter tip depicted in FIGS. 33and 34.

FIG. 36 is a fragmentary, isometric view of the catheter tip depicted inFIGS. 33-35, showing a flexible array of electrodes in a slightly-flexedconfiguration, simulating contact between the array of electrodes and acardiac wall.

FIG. 37 depicts the catheter shown in FIGS. 33-36 with the array ofelectrodes riding against trabeculated tissue.

FIG. 38 depicts the distal tip of a high-density mapping catheteraccording to a twelfth embodiment.

FIG. 39 depicts the distal portion of the high-density mapping catheteralso shown in FIG. 38, but overlying vasculature.

FIG. 40 depicts a tip portion of a high-density mapping catheteraccording to a thirteenth embodiment.

FIG. 41 depicts the distal portion of the high-density mapping catheteralso shown in FIG. 40, but overlying vasculature.

FIG. 42 is an isometric view of a high-density mapping catheter similarto that shown in FIGS. 40 and 41, but also comprising two tethers.

FIG. 43 depicts the distal tip of a high-density mapping catheteraccording to a fourteenth embodiment.

FIG. 44 depicts a high-density mapping catheter most similar to thecatheter depicted in FIG. 43, but also comprising an irrigation portnear a distal edge of a proximal bushing.

FIG. 45 is an enlarged, fragmentary view of a portion of thehigh-density mapping catheter depicted in FIG. 44, clearly showing theirrigation port.

FIG. 46 is an enlarged, isometric view of an embodiment of ahigh-density mapping catheter comprising a location sensor mounted inthe catheter shaft proximal to a proximal bushing.

FIG. 47 is an exploded, isometric view of a delivery adapter and aguiding sheath.

FIGS. 48A-48F depict a series of views showing how a delivery adaptersuch as the one depicted in FIG. 47 may be used with a dilator fordelivering a paddle catheter into a guiding sheath.

DETAILED DESCRIPTION OF EMBODIMENTS

Several embodiments of flexible, high-density mapping catheters andmap-ablate catheters are disclosed herein. In general, the tip portionsof these various catheters comprise an underlying support framework thatis adapted to conform to and remain in contact with tissue (e.g., abeating heart wall). Details of the various embodiments of the presentdisclosure are described below with specific reference to the figures.

FIGS. 1 and 2 depict, and FIG. 3 relates to, a tip portion 10 ^(A) of ahigh-density mapping catheter according to a first embodiment. As shownin FIG. 1, the tip portion 10 ^(A) includes interlocking rings or bands12 of nonconductive material (e.g., polyether-etherketone or PEEK)forming the underlying support framework for a plurality ofmicroelectrodes. In this embodiment, a circumferential or helicalthrough-cut pattern 14 defines a plurality of dovetail surfaces 16. Eachdovetail surface has a microelectrode 18 attached to it, therebydefining a flexible array of microelectrodes that are arranged incircumferential rings or bands. The electrodes 18 are also aligned inlongitudinally-extending (e.g., parallel to a catheter longitudinal axis20) rows of electrodes that are able to flex or move slightly relativeto each other during use of the catheter. The nonconductive materialindividually insulates each microelectrode.

The nonconductive substrate on which the button electrodes 18 aremounted may comprise PEEK. The tip 10 ^(A) includes a radiopaque tip cap22 that facilitates fluoroscopy visualization. The tip cap may be domedshaped, hemispherical, flat-topped, tapered, or any other desiredgeneral shape.

In this embodiment of the tip portion 10 ^(A), there are sixty-fourdiscrete microelectrodes 18, and a separate lead (shown in, for example,FIGS. 15 and 16) wire extends to each of these electrodes from theproximal end of the catheter. In a preferred version of this catheter,the catheter is either 7F or 7.5F. The flexible tip helps to facilitateand ensure stability during, for example, cardiac motion, which in turnmakes it possible to accurately map cardiac electrical activity becauseof the sustained electrode contact that is possible. The circumferentialor helical cuts 14, which may be formed by a laser, create a pluralityof serpentine gaps that permit the tip to flex as the cardiac wall movesin a beating heart. When a plurality of circumferential through-cuts areused, this creates a plurality of dovetailed (or ‘saw-toothed’) bands12. FIG. 3 depicts the flat-pattern design for one of these bands 12according to the first embodiment. As clearly shown in FIG. 3, thepattern includes a circumferential waistline or ring 24 defined betweena circumferentially-extending proximal edge 26 and acircumferentially-extending distal edge 28. Each of these edges isinterrupted by a plurality of proximally-extending pads 30 ordistally-extending pads 32. Each pad in this embodiment has the shape ofa truncated isosceles triangle with sides S and a base B. Two adjacentproximally-extending pads define a proximally-opening pocket 34 betweenthem. Similarly, on the opposite side of the circumferential waistline24, two distally-extending pads 32 that are adjacent to each otherdefine a distally-opening pocket 36.

As may be clearly seen in FIGS. 1 and 2, when two of these dovetailedbands are connected, each distally-extending pad 32 flexibly interlocksin a proximally-opening dovetailed pocket 34, and eachproximally-extending pad 30 flexibly interlocks in a distally-openingdovetail pocket 36. It is also shown in FIG. 3, each pad 30, 32, in thisembodiment, includes an aperture 38 in which a microelectrode will bemounted. Each aperture extends through a pad, from a pad outer surfaceto a pad inner surface.

Rather than having circumferential through-cuts 14, which define aplurality of individual electrode-carrier bands, the flexible tipdepicted in FIGS. 1 and 2 could be formed by a continuous helical cut.

FIGS. 4 and 5 are similar to FIGS. 1 and 2, respectively, but depict atip portion 10 ^(B) of a high-density mapping catheter according to asecond embodiment. In this embodiment, circumferential through-cuts 40define a plurality of discs 42 on which microelectrodes 18 are mounted.Alternatively, a helical cut could be used to form the flexible tipconfiguration shown in FIGS. 4 and 5. As with the embodiment shown inFIGS. 1 and 2, in the embodiment depicted in FIGS. 4 and 5, themicroelectrodes 18 are mounted in a nonconductive material such as PEEK.

A third embodiment of a tip portion 10 ^(C) is depicted in FIGS. 6 and7. In this embodiment, however, unlike the embodiment 10 ^(A) shown inFIGS. 1 and 2, the interlocking, dovetailed pattern is formed fromconductive material since this is an ablation tip. As shown to bestadvantage in FIG. 7, the distal end 44 of this flexible ablation tipincludes a pair of symmetrically-placed, high-density microelectrodes 46for mapping. As also shown to best advantage in FIG. 7, thisconfiguration includes two front-facing irrigation ports 48, and athermocouple or a temperature sensor 50. The mapping electrodes 46 aremounted in a nonconductive insert 52 to electrically insulate thesemapping electrodes from the remainder of the ablation tip. In thisparticular configuration, the flexible ablation tip is 4 millimeterslong. It should also be noted that, in this embodiment, the pads andpockets defined by the serpentine cuts 54 are smaller than thecorresponding pads and pockets depicted in, for example, FIGS. 1 and 2.In this ablation tip embodiment 10 ^(C), the individual pads 56 do notcarry microelectrodes and, therefore, the pads can be smaller in thisconfiguration of the ablation tip than they are in the high-densitymapping tips.

FIGS. 8 and 9 depict an ablation tip portion 10 ^(D) and high-densitymapping electrode according to a fourth embodiment. This embodiment is a7.5 Fr catheter having a 4.0 millimeters long, flexible ablationelectrode manufactured from, for example, platinum. In this design, fourhigh-density mapping electrodes 58 are mounted through the distal pads60 of pad structures. Also, each pad structure includes a larger distalpad and a smaller proximal pad 62; and each microelectrode 58 is mountedthrough an aperture 64 extending through a distal pad 60. In thisconfiguration 10 ^(D), two carrier bands are interconnected by a linkingband 66, a most-proximal carrier band 62 is connected with the distalend 68 of the catheter shaft 70, and a most-distal carrier band isconnected to an end cap 72. In this embodiment, each of the four mappingelectrodes is individually insulated and has its own lead wire (shownin, for example, FIGS. 5. And 6) extending from the electrode 58 out theproximal end of the catheter. Similar to what occurs in each of theembodiments already discussed, this is an irrigated configuration. Thus,during use of the catheter, irrigant (e.g., cooled saline) is routedfrom the proximal end of the catheter, through the catheter shaft, andout of the serpentine gaps formed in the tip.

FIGS. 10-16 provide details concerning the tip portion 10 ^(E) of ahigh-density mapping catheter according to a fifth embodiment. As shownto good advantage in FIG. 11, this catheter tip 10 ^(E) gets itsflexibility from a plurality of circumferential, dovetail cuts thatdefine a plurality of serpentine gaps 74 between alternatingelectrode-carrier bands (or carrier bands) 76 and linking bands 78. Theworking portion of the embodiment 10 ^(E) depicted in FIG. 11 isapproximately 20 millimeters long (see dimension L in FIGS. 11 and 12)and has a diameter of 7 Fr to 7.5 Fr (see dimension D in FIG. 11). Inthis embodiment, the longitudinal electrode spacing between adjacentmicroelectrode (see dimension S_(L) in FIGS. 11 and 12) is approximately1.8 millimeters, and the circumferential electrode spacing betweenadjacent microelectrode (see dimension S_(C) in FIG. 12) is alsoapproximately 1.8 millimeters. An end cap 104 may also be present asshown in, for example, FIGS. 10 and 11.

As shown to good advantage in FIG. 12, the fifth embodiment 10 ^(E)shows a plurality of electrode-carrier bands 76 separated by a pluralityof linking bands 78. Thus, there is one linking band between directlyadjacent pairs of carrier bands. In this configuration, each carrierband includes a plurality of bowtie-shaped or hourglass-shapedstructures 80 (see for example, FIGS. 13 and 14). Further, in thisconfiguration, each of these bowtie-shaped structures 80 comprises adistal pad 82 and a proximal pad 84, separated by a narrowed region orwaist 86. In this configuration, each distal pad 82 of each carrier band76 has an electrode-mounting aperture 88 (e.g., 0.9 mm diameter) throughit.

Further, as shown to best advantage in FIGS. 12 and 14, there is acircumferential connector 90 between each pair of adjacent padstructures. The circumferential connectors 90, along with the waist 86of each pad structure 80, together define a circumferential ring. Inthis embodiment, the bowtie-shaped or hourglass-shaped pad structures 80are essentially symmetrical about the waist 86 except for the existenceof an electrode-mounting aperture 88 in each of the distal pads 82.

As shown in FIG. 14, a distally-opening slot 92 is present betweenadjacent, distally-extending pads 82. Similarly, a proximally-openingslot 94 is present between adjacent, proximally-extending pads 84.Looking at a single electrode-carrier band, thecircumferentially-extending pad connectors 90, together with the waists86 of each pad structure 80, define a carrier band waistline thatextends around the circumference of the tip portion 10 ^(E) of thecatheter.

In this configuration, as shown in FIG. 12, each linking band 78 alsocomprises a connected series of bowtie-shaped structures 96. In thisparticular embodiment, the bowtie-shaped pad structures 96 of thelinking bands 78 are larger than the bowtie-shaped pad structures 80 ofthe carrier bands 76.

FIGS. 15 and 16 are views with portions of the catheter removed to showinner details of the catheter tip portion of 10 ^(E). In FIG. 15, it ispossible to see the individual lead wires 98 extending longitudinallythrough the catheter shaft and connecting with each of themicroelectrodes 18. It is also possible to see an internal spring 100 inthis figure. This spring helps the tip portion 10 ^(E) of the cathetermaintain its flexibility, and it helps create the gaps between adjacentcarrier bands 76 and linking bands 78. FIG. 16 depicts an internalirrigation lumen 102 that acts as an irrigant distribution manifold.

The button electrodes or microelectrodes 18 may have a diameter between0.7 and 0.9 millimeters. The lead wires extending through the cathetershaft to each of these electrodes may comprise 38 AWG wire. Aspreviously described in connection with other embodiments, an end cap104 may be metallic, or otherwise radiopaque, to facilitatevisualization of the catheter tip during use of a fluoroscope.

FIGS. 17-26 depict aspects of a sixth embodiment of a tip portion 10^(F). FIG. 17 depicts a cylindrical-shaped portion 106 of nonconductivematerial that has been laser cut to define an interlocking, but flexiblepattern 108 (see FIG. 18). FIG. 18 shows what that pattern 108 lookslike when it is laid out flat rather than having the cylindrical shapedepicted in FIG. 17.

In this embodiment, a plurality of electrode-carrier bands (or carrierbands) 110 and a plurality of linking bands 112 are present. FIG. 19 issimilar to FIG. 14, but shows adjacent pad structures 113 according tothe sixth embodiment, as also shown in FIGS. 17 and 18. In thisconfiguration, the carrier bands 110 are not completely separate fromthe adjacent linking bands 112. In particular, as may be clearly seen inFIGS. 17 and 18, this embodiment includes a plurality of inter-bandbridges or connectors 114. All of the bands 110, 112 are thereby looselyinterconnected, and one band cannot move completely independently of anyother band comprising the working portion of the high-density mappingcatheter tip 10 ^(F).

As also clearly shown in FIGS. 17-19, in this embodiment, each padstructure 113 is not the symmetrical bowtie-shaped structure 80 depictedin, for example, FIG. 12. Rather, in the sixth embodiment, the distaltabs 116 of each pad structure 113 are larger than the correspondingproximal pads 118 of the pad structure 113. The electrode apertures 120extend through this larger distal pad 116.

As shown to good advantage in FIG. 19, slots are formed between adjacentpad structures 113. In particular, a relatively shallow,proximally-opening tab slot 122 is formed between adjacent proximal pads118. Similarly, a relatively deep, distally-opening tab slot 124 isformed between adjacent pairs of distal pads 116. As described abovewith reference to FIG. 14, circumferentially-extending connectors 126are again present between adjacent pad structures 113. All of theseconnectors on a single carrier band 110, together with the waists 128 ofeach pad structure comprising part of that same carrier band, form acarrier band waistline.

FIG. 20 depicts a tab structure 130 from a linking band 112. Eachlinking band comprises a plurality of these tab structures. Each tabstructure includes a relatively-longer, proximally-extending tab (or‘proximal tab’) 132 in a relatively-shorter, distally-extending tab (or‘distal tab’) 134. FIG. 21 depicts two adjacent tab structures 130 of asingle linking band 112. A proximally-opening pocket 136 is definedbetween adjacent proximal tabs 134. Similarly, a distally-opening pocketis defined between adjacent distal tabs. A circumferentially-extending,tab-structure connector 140 connects adjacent tab structures 130 andhelps to form the proximally-opening pocket 136 and a distally-openingpocket 138. In other words, each linking band 112 includes acircumferentially-extending proximal edge 142 and acircumferentially-extending distal edge 144. The proximal edge defines aseries of proximally-extending tabs 132 and proximally-opening pockets136, and the distal edge 144 of each linking band 112 forms a pluralityof distally-extending tabs and distally-opening pockets 138.

FIG. 22 also relates to the sixth embodiment. In particular, FIG. 22depicts a single linking band 112 (on the left) flexibly interlockedwith a single carrier band 110 (on the right). As shown, eachproximally-extending tab 132 is flexibly interlocked in a correspondingdistally-opening slot 124 in a carrier band 110. Similarly, eachdistally-extending pad 116 of the carrier band is flexibly interlockedin a corresponding proximally-opening pocket 136 in the linking band112.

Each tab structure of the linking band is an asymmetrical bowtieconfiguration. Similarly, each pad structure 113 of the carrier band 110is also an asymmetrical bowtie configuration. The serpentine gapextending between the linking band 112 and the carrier band 110 (e.g., alaser cut gap) defines the tabs and the pockets of the linking band, anddefine the complementary pads and slots, respectively, of the carrierbands.

FIG. 23 depicts a fully-assembled tip portion 10 ^(F) of a high-densitymapping catheter according to the sixth embodiment. The fully assembledtip includes a most-proximal band (or shaft-transition band) 146, and amost-distal band (or end-cap-transition band) 148. An end cap 150 may beplatinum or some other radiopaque material to facilitate visualizationon a fluoroscopy screen. As may be seen in FIG. 23, the buttonelectrodes or microelectrodes 18 are slightly raised off the outersurface of the laser cut PEEK material. This is also clearly visible inFIG. 24, which shows the catheter tip in a slightly-flexedconfiguration. With the electrodes raised slightly as shown, betterelectrical contact can be maintained between the electrodes and thetissue. In the embodiment depicted in FIGS. 17-26, there are thirty-twomapping electrodes 18 mounted in the laser-cut PEEK material. In thisparticular design, the catheter shaft is 7 Fr or 7.5 Fr.

FIGS. 25 and 26 also depict the sixth embodiment. In particular, FIG. 25shows an entire catheter 152, including an electrical connector 154 anda control handle 156 near the proximal portion of the catheter and aflexible high-density mapping tip 10 ^(F) at the distal end of thecatheter 152. FIG. 26 is an enlarged view of the circled portion of FIG.25.

FIG. 27 depicts the distal tip portion 10 ^(G) of a high-density mappingcatheter according to a seventh embodiment. Similar to some of theconfigurations discussed above, this tip portion includes a metallic cap(e.g., a platinum cap) 158 or otherwise radiopaque cap to facilitatevisualization on fluoroscopy. This specific embodiment 10 ^(G) isdifferent from the embodiment 10 ^(F) depicted, for example, in FIG. 23,since the electrode apertures 160 in this embodiment are located throughthe distal pads 162 of pad structures of electrode carrier bands 164that are relatively smaller than the tab structures of the linking bands166. In this seventh embodiment, each electrode-carrier band 164includes a plurality of bowtie-shaped pad structures that arecircumferentially arranged around the longitudinal axis of the catheter.Similarly, each linking band 166 comprises a plurality of bowtie-shapedtab structures also arranged circumferentially around the catheterlongitudinal axis. In this particular configuration of the tip portion10 ^(G), however, the bowtie-shaped tab structures are relatively largerthan the bowtie-shaped pad structures of the electrode-carrier bands164. By changing the relative size of the distal and proximal tabs, andthe relative size of the corresponding or related distal and proximalpads, the performance characteristics of the tip portion of thehigh-density mapping catheter can be adjusted.

FIG. 28 depicts an eighth embodiment of a high-density mapping tipportion 10 ^(H). In this embodiment, a 7 Fr catheter includes a flexiblearray of microelectrodes 18 that is similar to, but shorter than, theflexible array of microelectrodes depicted in, for example, FIGS. 23-26.In this particular design, however, 1.0 mm ring electrodes 168, 170, 172are located at each longitudinal end of the flexible array of 0.9 mmdiameter microelectrodes 18. In the depicted embodiment, themost-proximal circumferential ring of microelectrodes 18 is locatedapproximately 1.2 mm (see dimension SR in FIG. 28) from themost-proximal circumferential edge 171 of array. As shown, there aresixteen microelectrodes arranged in four longitudinally-extending rowsof four electrodes, each row radially offset from the next row by 90°.The longitudinal spacing between adjacent microelectrodes may be, forexample, 1.8 mm. There are two ring electrodes 168, 170 spaced 1.0 mmfrom each other and located proximal to the most-proximalcircumferential edge 171 of the flexible array of microelectrodes. Thereis a third 1.0 mm ring electrode 172 located distal of the most-distaledge 173 of the flexible array of microelectrodes. In this particularconfiguration, there is also a 1.0 mm long metal tip 174 that could beused as an additional electrode.

FIGS. 29 and 30 depict the distal portion 10 ^(I) of a map-and-ablatecatheter according to a ninth embodiment. Similar to what is shown inFIG. 28, the ninth embodiment shown in FIGS. 29 and 30 includes aflexible array of microelectrodes 18 comprising sixteen microelectrodesarranged in four longitudinally extending rows of four where each ofthese rows is radially offset by 90° from the next adjacent row ofelectrodes. In this embodiment, however, the most-distal end of thecatheter comprises a flexible ablation tip 176. This ablation tip maybe, for example, a Cool Flex™ ablation tip sold by St. Jude Medical,Inc. of St. Paul, Minn. During use, irrigant would flow down thecatheter shaft and exit through the serpentine gaps in the flexiblearray of microelectrodes and through the openings in the flexibleablation tip. This tip would advantageously conform to the cardiactissue during both mapping and ablation procedures.

FIGS. 31 and 32 depict a tip portion 10 ^(J) of a map-and-ablatecatheter according to a tenth embodiment. Moving distally down thecatheter shaft toward the most-distal end, two 1.0 mm ring electrodesare encountered, including a most-proximal ring 170 electrode and amost-distal ring electrode 168. Next, a proximal short flexible array178 of eight 0.9 mm diameter microelectrodes, mounted in four rows oftwo microelectrodes, is encountered. In this embodiment, thesemicroelectrodes project from the outer surface of the catheterapproximately 0.18 mm and are longitudinally spaced from each other byapproximately 1.8 mm. Connected to the distal-side of this shortflexible array of microelectrodes is an ablation region 180 that isapproximately 3.5 mm long and that includes a plurality of irrigationholes 182. Distal of the ablation region is another, rather shortflexible array 184 of microelectrodes. In this particular configuration,the distal flexible array 184 of microelectrodes is similar to theproximal, flexible array 178 of microelectrodes. Finally, in this mapablate catheter, the distal end includes a metallic cap 186 that may beused for mapping, ablation, and/or visualization on fluoroscopy.

FIGS. 33-37 depict a tip portion 10 ^(K) comprising a flexible array ofmicroelectrodes according to an eleventh embodiment. This planar array(or ‘paddle’ configuration) of microelectrodes comprises fourside-by-side, longitudinally-extending arms 188, 190, 192, 194 formingthe flexible framework on which the thirty-two 1.0 mm long×0.8 mmdiameter ring electrodes 196 are carried. As discussed further below, afew of these ring electrodes (see, for example, rings 198 and 200 inFIG. 33) may be slightly longer. The four ring-electrode-carrier armscomprise a first outboard arm 188, a second outboard arm 190, a firstinboard arm 192, and a second inboard arm 194. These arms are laterallyseparated from each other by approximately 3.3 mm in this embodiment.Each of the four arms carries eight small ring electrodes 196, spacedalong its length. In the depicted embodiment, these small ring-shapedmicroelectrodes are longitudinally separated from each other byapproximately 1.0 mm. Although each of the paddle catheters depicted inFIGS. 33-42 shows four arms, the paddle could comprise more or fewerarms.

FIG. 33 is an isometric, fragmentary view of the planar array. As shownto best advantage in FIG. 34, the most-distal ring electrode 198 on thefirst outboard arm 188 is slightly enlarged as is the most-proximal ringelectrode 200 on the second outboard arm 190. These slightly enlargedelectrodes 198, 200 (e.g., in the depicted embodiment, thesemicroelectrodes are slightly longer than the other ring electrodes) canbe used, for example, for more precise localization of the flexiblearray in mapping and navigation systems. It is also possible to driveablation current between these enlarged electrodes, if desired, forbipolar ablation, or, alternatively to drive ablation current inunipolar mode between one or both of these enlarged ring electrodes and,for example a patch electrode located on a patient (e.g., on thepatient's back). Similarly, the microelectrodes 196 (on this or any ofthe other paddle catheters) can be used to perform unipolar or bipolarablation. Alternatively or concurrently, current could travel betweenone or more of the enlarged electrodes and any one or all of themicroelectrodes. This unipolar or bipolar ablation can create specificlines or patterns of lesions. As also may be seen in FIG. 34, there maybe a distal member (or ‘button’) 202 where one or more of the arms cometogether. This distal member may be constructed from metal or some otherradiopaque material to provide fluoroscopy visualization andsemi-independent planar movement between the outer and inner arms.

As shown to best advantage in FIG. 37, the planar, flexible arms conformto trabeculated tissue 204, enabling a physician to maintain contactbetween several of the electrodes and the tissue. This enhances theaccuracy, and the corresponding diagnostic value, of the recordedinformation concerning the heart's electrical activity.

FIGS. 38 and 39 depict a flexible array of microelectrodes at the tipportion 10 ^(L) of a high-density mapping catheter according to atwelfth embodiment. In this configuration, there are four 1.0 mm ringelectrodes (depicted with a 2.0 mm longitudinal spacing) mounted on thedistal end of the catheter shaft, proximal to a proximal bushing 206 andto the proximal ends of ring electrode carrier arms 188′, 190′, 192′,194′. In this embodiment, each of the four electrode carrying arms haseight small ring electrodes 196 (microelectrodes) mounted on it. Thefour arms are designed to maintain the thirty-two small ring electrodesin a spaced relationship so that each small ring electrode can captureseparate data about the electrical activity of the cardiac tissueadjacent to the microelectrodes.

FIGS. 40-42 depict two variations 10 ^(M), 10 ^(N) of a similar tipportion comprising a flexible array of microelectrodes 196′. In bothvariations of this particular configuration, there are sixteen smallring electrodes 196′ mounted on four small arms 188″, 190″, 192″, 194″rather than the thirty-two ring electrodes 196 depicted in FIGS. 38 and39. These small ring electrodes (1.0 mm long×0.8 mm diameter) arelongitudinally separated from each other by approximately 3.0 mm in thisembodiment, and the electrode carrying arms are laterally separated fromeach other by approximately 4.0 mm. Further, in the variation 10 ^(N)depicted in FIG. 42, the high-density mapping catheter also includes twotethers 210 extending transverse across and interconnecting the fourelectrode carrying arms. Although two tethers are shown in FIG. 42, anynumber of tethers could be used, including a single tether. The tetheror tethers 210 help maintain a predictable relationship between theelectrode carrying arms 188″, 190″, 192″, 194″ by controlling, forexample, how each electrode carrying arm may move relative to the otherelectrode carrying arms. Each tether 210 may comprise a tensile element,such as slender mono- or multi-filament nylon thread or suture-likematerial. The tethers may be connected with or to the electrode carryingarm in a variety of ways. In FIG. 42, for example, the tethers 210 havebeen adhered or ultrasonically welded to each of the electrode carryingarms 188″, 190″, 192″, 194″. Alternatively, a tether could be tied to orlooped around the arms. Reflowing the device during the manufacturingprocess may allow the tether or tethers to become incorporated into thearms polymer insulation, thereby securing the tether to the arms andminimizing the need for tying, looping, gluing, or otherwise attachingthe tethers to the arms. The tethers 210 are configured to also collapseor fold during insertion of the catheter into a delivery sheath orintroducer.

FIG. 43 depicts yet another embodiment of a tip portion 10 ^(O)comprising a flexible array of microelectrodes. This configuration ismost similar to the first variation 10 ^(M) of the thirteenthembodiment, which is depicted in FIGS. 40 and 41. However, in thefourteenth embodiment, there are two additional ring electrodes 212mounted near the distal end of each outboard arm.

FIG. 44 depicts an alternative variation of the high-density mappingcatheter embodiment 108 depicted in FIG. 43. In particular, in FIG. 44,an irrigation port 214 is present at the distal end of a proximalbushing 206′, and the irrigation port is positioned to deliver irrigantto or near the point where the electrode carrying arms exit from thedistal end of the proximal bushing that is mounted on the distal end ofthe catheter shaft in this embodiment. If desired, a second irrigationport (not shown) may be located near the distal intersection of theelectrode carrying arms. In fact, if desired, multiple irrigation ports(not shown) could be present at various positions along the electrodecarrying arms 188″, 190″, 192″, 194″. FIG. 45 is an enlarged,fragmentary view of the irrigation port 214 on the proximal bushing206′. Further, while only one irrigation port 214 is illustrated on theproximal bushing 206′, multiple irrigation ports could be present on theproximal bushing (e.g., one or more on each side of the planar array ofmicroelectrodes) to provide more uniform irrigant distribution at ornear the proximal apex of the arms 188″, 190″, 192″, 194″. Likewise, adistal irrigation port set (not shown) comprising multiple ports couldbe included at or near the distal apex of the arms 188″, 190″, 192″,194″.

FIG. 46 is a fragmentary, isometric view of the distal portion of thecatheter shaft of a high-density mapping catheter. In this view,portions of the catheter shaft have been removed to reveal a sensor 216located just proximal to the proximal bushing. A variety of sensors maybe incorporated at this location, or at similar locations, in thehigh-density mapping catheters described herein. These sensors may bemounted in the catheter shaft, as shown in FIG. 46, or they may bemounted at other locations (e.g., along the electrode carrying arms ofthe high-density mapping paddle and/or at the distal apex or joint ofthe tip portion). In one embodiment, the sensor 216 is a magnetic fieldsensor configured for use with an electromagnetic localization systemsuch as the MediGuide™ System sold by St. Jude Medical, Inc. of St.Paul, Minn.

FIG. 47 is an exploded, isometric view of one embodiment of a deliveryadapter 218 designed to facilitate delivery of a paddle catheter intoand through a guiding sheath or introducer 220 having a circular crosssection. As depicted in this figure, the delivery adapter 218 comprisesa first portion 218A having pins 222 extending therefrom, and a secondportion 218B having complementary pin-receiving holes 224 therein. Whenthese portions 218A, 218B are assembled, a proximal pocket configured tosupport or hold the distal end of a dilator hub 228 (labeled in FIGS.48A and 48B) is formed. In particular, the first portion 218A of thedelivery adapter includes a first part 226A of that pocket, and thesecond portion 218B of the delivery adapter comprises a second part 226Bof the pocket. In this particular embodiment, a dilator shaft channel isalso present and comprises a first trough 230A formed in the firstportion 218A of the delivery adapter 218 and a second trough 230B formedin the second portion 218B of the delivery adapter 218. Also, the distalside of the delivery adapter, in this embodiment, comprises a threadedhole (e.g., a female luer lock) 232A, 232B adapted to thread onto ashaft or fitting (e.g., a male luer lock) 234 extending proximally fromthe proximal end of the guiding sheath 220.

As best seen in FIG. 47, the interior of the delivery adapter, betweenthe proximal pocket 226A, 226B and the threaded hole 232A, 232B definesa hollow compression or folding cone 236A, 236B. In one embodiment, forexample, the lateral cross-sectional shape of the proximal end of thiscompression cone is elliptical or nearly elliptical, and the lateralcross-sectional shape of the distal-most portion of the compression coneis circular or near circular, matching the channel through a hub 238 ofthe guiding sheath 220. The compression cone is thereby configured oradapted to compress the relatively flat paddle of the high-densitymapping catheter into a configuration having a substantially circularcross-sectional shape or other shape that fits into the proximal openingin the guiding sheath hub 238. It should also be noted that the deliveryadapter may be splittable for easy removal when used with a splittableguiding sheath.

Referring now most specifically to the various views comprising FIGS.48A-48F, one use of the delivery adapter 218 just described inconnection with FIG. 47 is described next. In this use, a dilator 240 isinserted into and through the delivery adapter 218 and seated in thepocket 226A, 226B formed in the proximal side of the assembled deliveryadapter. The assembled delivery adapter 218, with the dilator 240 inplace, is then mounted to the guiding sheath 220 as shown in FIG. 48A.The dilator 240, shown by itself in FIG. 48B, is then removed from thedelivery adapter 218 and guiding sheath 220, as may be seen in theleft-hand portion of FIG. 48C.

Next, as also shown in view FIG. 48C, the paddle 242 of a high-densitymapping catheter is inserted into the proximal end of the compressioncone 236A, 236B of the delivery adapter. In FIG. 48D, the electrodecarrying arms of the paddle have been inserted further into thecompression cone. As the electrode carrying arms of the paddle impactthe angled side surfaces of the compression cone formed in the deliveryadapter 218, the electrode carrying arms are compressed towards eachother. When the arms have been sufficiently compressed together (i.e.,into a side-by-side, touching or near-touching configuration), thepaddle then fits into the proximal end of the port through the guidingsheath or introducer 220 and may be pushed through the hemostasis valve(not shown) in the hub 238 at the proximal end of the guiding sheath220. As shown in FIG. 48E, as the paddle portion 242 of the high-densitymapping catheter exits from the distal end of the guiding sheath 220,the electrode carrying arms comprising the paddle remain compressedtogether. Once the electrode carrying arms of the paddle exit from thedistal end of the shaft or tube of the guiding sheath, the electrodecarrying arms expand back into the paddle configuration, as best shownin FIG. 48F.

In each of the embodiments depicted in, for example, FIGS. 33-46, one ormore of the ring electrodes 208 could be used to send pacing signals to,for example, cardiac tissue. Further, the arms (or the understructure ofthe arms) comprising the paddle structure (or multi-arm,electrode-carrying, flexible framework) at the distal end of thecatheters depicted in FIGS. 33-46 are preferably constructed from aflexible or spring-like material such as Nitinol. The construction(including, for example, the length and/or diameter of the arms) andmaterial of the arms can be adjusted or tailored to be created, forexample, desired resiliency, flexibility, foldability, conformability,and stiffness characteristics, including one or more characteristicsthat may vary from the proximal end of a single arm to the distal end ofthat arm, or between or among the plurality of arms comprising a singlepaddle structure. The foldability of materials such as Nitinol providethe additional advantage of facilitating insertion of the paddlestructure into a delivery catheter or introducer, whether duringdelivery of the catheter into the body or removal of the catheter fromthe body at the end of a procedure. Although a short guide sheath 220(used, for example, for epicardial access) is depicted in FIGS. 47 and48A-48F, a longer guide sheath (used, for example, to access the heartfrom a femoral access point) could be used to introduce the flexiblehigh-density mapping and ablation tips described herein.

Among other things, the disclosed catheters, with their plurality ofmicroelectrodes, are useful to (1) define regional propagation maps onone centimeter square areas within the atrial walls of the heart; (2)identify complex fractionated atrial electrograms for ablation; (3)identify localized, focal potentials between the microelectrodes forhigher electrogram resolution; and/or (4) more precisely target areasfor ablation. These mapping catheters and ablation catheters areconstructed to conform to, and remain in contact with, cardiac tissuedespite potentially erratic cardiac motion. Such enhanced stability ofthe catheter on a heart wall during cardiac motion provides moreaccurate mapping and ablation due to sustained tissue-electrode contact.Additionally, the catheters described herein may be useful forepicardial and/or endocardial use. For example, the planar arrayembodiments depicted in FIGS. 33-48F may be used in an epicardialprocedure where the planar array of microelectrodes is positionedbetween the myocardial surface and the pericardium. Alternatively theplanar array embodiments may be used in an endocardial procedure toquickly sweep and/or analyze the inner surfaces of the myocardium andquickly create high-density maps of the heart tissue's electricalproperties.

Although several embodiments have been described above with a certaindegree of particularity, those skilled in the art could make numerousalterations to the disclosed embodiments without departing from thespirit of the present disclosure. It is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative only and not limiting. Changes indetail or structure may be made without departing from the presentteachings. The foregoing description and following claims are intendedto cover all such modifications and variations.

Various embodiments are described herein of various apparatuses,systems, and methods. Numerous specific details are set forth to providea thorough understanding of the overall structure, function,manufacture, and use of the embodiments as described in thespecification and illustrated in the accompanying drawings. It will beunderstood by those skilled in the art, however, that the embodimentsmay be practiced without such specific details. In other instances,well-known operations, components, and elements have not been describedin detail so as not to obscure the embodiments described in thespecification. Those of ordinary skill in the art will understand thatthe embodiments described and illustrated herein are non-limitingexamples, and thus it can be appreciated that the specific structuraland functional details disclosed herein may be representative and do notnecessarily limit the scope of the embodiments, the scope of which isdefined solely by the appended claims.

Reference throughout the specification to “various embodiments,” “someembodiments,” “one embodiment,” “an embodiment,” or the like, means thata particular feature, structure, or characteristic described inconnection with the embodiment is included in at least one embodiment.Thus, appearances of the phrases “in various embodiments,” “in someembodiments,” “in one embodiment,” “in an embodiment,” or the like, inplaces throughout the specification are not necessarily all referring tothe same embodiment. Furthermore, the particular features, structures,or characteristics may be combined in any suitable manner in one or moreembodiments. Thus, the particular features, structures, orcharacteristics illustrated or described in connection with oneembodiment may be combined, in whole or in part, with the featuresstructures, or characteristics of one or more other embodiments withoutlimitation.

It will be appreciated that the terms “proximal” and “distal” may beused throughout the specification with reference to a clinicianmanipulating one end of an instrument used to treat a patient. The term“proximal” refers to the portion of the instrument closest to theclinician and the term “distal” refers to the portion located furthestfrom the clinician. It will be further appreciated that for concisenessand clarity, spatial terms such as “vertical,” “horizontal,” “up,” and“down” may be used herein with respect to the illustrated embodiments.However, surgical instruments may be used in many orientations andpositions, and these terms are not intended to be limiting and absolute.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

1. (canceled)
 2. A high-density mapping catheter comprising: a cathetershaft comprising a proximal end and a distal end, the catheter shaftdefining a catheter shaft longitudinal axis extending between theproximal end and the distal end; a flexible tip portion fixed adjacentto the distal end of the catheter shaft, the flexible tip portioncomprising a flexible framework comprising nonconductive materialforming a plurality of electrode-carrying arms, wherein each of theplurality of electrode-carrying arms converges with at least one otherof the plurality of electrode-carrying arms at a distal end of theflexible tip portion; and a plurality of microelectrodes mounted on theflexible framework and forming a flexible, planar array ofmicroelectrodes adapted to conform to tissue, wherein the plurality ofmicroelectrodes are mapping electrodes, wherein the flexible frameworkis configured to facilitate relative movement among at least some of theplurality of microelectrodes relative to other of the plurality ofmicroelectrodes, and wherein the nonconductive material insulates eachof the plurality of microelectrodes from other of the plurality ofmicroelectrodes.
 3. The high-density mapping catheter of claim 2,wherein the plurality of microelectrodes are arranged in a plurality ofrows, wherein each row is distributed along a different one of theplurality of electrode-carrying arms and the plurality of rows isaligned parallel to the catheter shaft longitudinal axis.
 4. Thehigh-density mapping catheter of claim 3, wherein the plurality ofelectrode-carrying arms are configured to maintain the plurality ofmicroelectrodes in the plurality of rows in a spaced relationship suchthat each of the plurality of microelectrodes can capture separate dataabout the electrical activity of cardiac tissue adjacent to theplurality of microelectrodes.
 5. The high-density mapping catheter ofclaim 2, wherein the plurality of microelectrodes comprise between fourand sixty-four individual microelectrodes.
 6. The high-density mappingcatheter of claim 2, further comprising at least one ring electrodemounted on the catheter shaft adjacent to the flexible, planar array ofmicroelectrodes.
 7. The high-density mapping catheter of claim 2,further comprising at least one location sensor.
 8. The high-densitymapping catheter of claim 7, wherein the at least one location sensor ismounted in or on at least one of the following: the catheter shaft andthe distal end of the flexible tip portion.
 9. The high-density mappingcatheter of claim 7, wherein the at least one location sensor is amagnetic field sensor.
 10. The high-density mapping catheter of claim 2,wherein the flexible, planar array of microelectrodes comprises atwo-sided planar array of microelectrodes, wherein the microelectrodesare configured for contacting tissue on a front side and a back side ofthe planar array.
 11. The high-density mapping catheter of claim 2,wherein the microelectrodes are ring electrodes.
 12. A cathetercomprising: an elongated catheter body comprising a proximal end and adistal end, and defining a catheter longitudinal axis extending betweenthe proximal and distal ends; and a flexible tip assembly fixed at thedistal end of the catheter body and comprising a flexible framework ofnonconductive material, wherein the flexible framework comprises aplurality of electrode-carrying arms adapted to conform to tissue,wherein each of the plurality of electrode-carrying arms converges withat least one other of the plurality of electrode-carrying arms at adistal end of the flexible tip assembly, and wherein the flexible tipassembly further comprises: a plurality of microelectrodes arranged in aflexible, planar array comprising a plurality of rows oflongitudinally-aligned microelectrodes aligned parallel to the catheterlongitudinal axis and mounted on the plurality of electrode-carryingarms so that at least some of the plurality of microelectrodes aremoveable relative to other of the plurality of microelectrodes, whereineach row of microelectrodes is distributed along a different one of theplurality of electrode-carrying arms.
 13. The catheter of claim 12,wherein the plurality of electrode-carrying arms are configured tomaintain the plurality of microelectrodes in the plurality of rows in aspaced relationship such that each of the plurality of microelectrodescan capture separate data about the electrical activity of cardiactissue adjacent to the plurality of microelectrodes.
 14. The catheter ofclaim 12, wherein the plurality of microelectrodes are equally spacedalong each of the plurality of electrode-carrying arms.
 15. The catheterof claim 12, wherein the plurality of microelectrodes are configured foruse as mapping electrodes.
 16. The catheter of claim 15, wherein theplurality of microelectrodes are configured for use in unipolar orbipolar ablation.
 17. The catheter of claim 16, further comprising atemperature sensor.
 18. The catheter of claim 16, further comprising anirrigation port configured to deliver an irrigant on or adjacent to theplanar array of microelectrodes.
 19. The catheter of claim 16, furthercomprising an internal fluid delivery lumen configured to be fluidlycoupled to a source of irrigant and configured to deliver the irrigantto the flexible tip assembly.
 20. The catheter of claim 12, wherein theflexible, planar array of microelectrodes comprises a two-sided planararray of microelectrodes, wherein the microelectrodes are configured forcontacting tissue on a front side and a back side of the planar array.21. The catheter of claim 12, wherein the microelectrodes are ringelectrodes.